Syrian foreign ministry spokesman Jihad Makdissi has defected from President Bashar al-Assad's government and has left the country, a regional diplomatic source said on Monday.

"All I can say is that he is out of Syria," the source, who did not want to be named, told Reuters.

Lebanon's al-Manar Television said earlier that Makdissi had been sacked for making statements which did not reflect official positions.

The United States' concerns about Syria's intentions regarding use of chemical weapons is increasing, prompting Washington to prepare contingency plans, White House spokesman Jay Carney said on Monday.

Carney's comments came after Secretary of State Hillary Clinton warned that the United States would take action if Syria used the weapons. Carney declined to say what the contingency plans involved.

Separately, an EU official said that the European Union's office in Damascus is cutting back its activities in the Syrian capital to a minimum because of the security situation.

Meanwhile, The United Nations said it was withdrawing "all non-essential international staff" from Syria due to the worsening security situation, and was restricting remaining staff to the capital.

Up to 25 of about 100 international staff could leave this week, it said, adding that more armoured vehicles were needed following attacks on humanitarian aid convoys sometimes caught in crossfire between Syrian government and rebel forces.

"The U.N. has decided to send all non-essential international staff out of Syria and to halt all field trips outside of the capital for now," the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) said in a statement.

Earlier, The foreign ministry said in a
statement on state television on Monday that Syria would not use chemical
weapons, if it had them, against its own people.

"In response to the statements of the American secretary of state, who
warned Syria against using chemical weapons, Syria has stressed repeatedly that
it will not use these types of weapons, if they were available, under any
circumstances against its people," the statement said.

A
US State Department top official declared on condition of anonymity that even
if NATO foreign ministers approve Turkey's request to deploy Patriot missiles
on the border with Syria as expected, it will still take some weeks
to get them in, stressing that “this matter cannot take place immediately.”

The official, who is accompanying the US Secretary of State Hilary Clinton
during her European tour, noted that the US is optimistic that NATO will be
responding positively and will agree to help Turkey reinforce its air defenses,
during a meeting for NATO foreign ministers expected to be held on Tuesday and
Wednesday in Brussels.

An EgyptAir flight from Cairo to
Damascus turned back on Monday because of the "bad security
situation" at the Syrian capital's airport, an EgyptAir official said.

On the field

Syrian regime forces launched two
airstrikes on the rebel-held town of Beit Sahem in southern Damascus suburbs,
near the highway leading to Damascus International Airport on Monday, according to the
Syrian Observatory for Human Rights.

Earlier, Syria bombed a security building that had been taken over by rebels on
the Turkish border, wounding at least 11 people and sending dozens of civilians
fleeing across the frontier, a Turkish official
said.

In return, Turkey scrambled fighter jets along its border with Syria after
Syrian government forces bombed rebel positions in the frontier town of Ras
al-Ain and stray shells flew into Turkish territory, Turkish security sources
said.

Rebels overran Ras al-Ain almost a month ago in fighting which has triggered
some of the biggest refugee movements of Syria's 20-month civil war, and has
tested Turkey's resolve to defend itself against any spillover of violence.

The security sources said Turkish F-16 jets were scrambled from their base in
the southeastern city of Diyarbakir after the air raids on the Free Syrian
Army's headquarters in Ras al-Ain.

Shells landed in the Turkish town of Ceylanpinar, which abuts Ras al-Ain,
triggering panic, the sources said. It was not immediately clear whether the
shells were fired by forces loyal to President Bashar al-Assad or by the
rebels.

On the other hand, the Russian President Vladimir Putin headed for Turkey on
Monday for a one-day trip focused on trade that is likely to be overshadowed by
the two countries' differences over Syria.

On Sunday, Lebanese soldiers exchanged fire with Syrian rebels across their
border, media reports said, fueling concerns that the Arab Spring's longest and
deadliest revolt could spark a regional war.